Programmable Digital Glitch Filter
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
In a bar code reader, reflected light from the bar code is processed to produce a digital signal. A binary 1 may represent a black bar and a binary 0 represents a white space. The time duration in either state is directly proportional to the time the scanning beam was over the associated bar or space. White dust in the middle of a black bar introduces a 'glitch' into the data stream. The circuit described removes this glitch from the data stream. Glitches can be introduced by a variety of sources, other than dust, including dirt, ink, smudges, poor printing, paper texture, reflectivity changes and ambient light spikes. The digital glitch filter is programmable and filters any glitch of duration less than or equal to a specified glitch count.